This invention relates generally to central tire inflation systems (CTI Systems or CTIS) and, more particularly, to a method for adaptively controlling the demand pressure setting in a central tire inflation system in order to improve performance and prolong tire life.
Central tire inflation systems are well known as may be seen by reference to U.S. Pat. Nos. 4,640,331; 4,678,017; 4,754,792; 4,782,879; 4,804,027; 4,883,106; 4,898,216; 4,922,946; 4,924,926; 5,174,839; 5,253,687; 5,180,456; and published European Patent Applications 0,297,837; 0,352,921, the disclosures of which are incorporated herein by reference. Each of these systems allow a vehicle operator to remotely vary the air pressure in vehicle tires to dynamically alter the tractive ability of the tires depending upon the terrain and the load carried by the vehicle.
In order to accomplish this, a system controller is preprogrammed with a series of tire pressures, each corresponding to a particular "operating mode" or set of conditions under which the vehicle is to be operated. These pressures are selected based upon a number of factors including tire manufacturer's recommendations and the anticipated loads to be carried and speeds to be driven. As the vehicle is operated, the driver indicates the current operating mode via a control panel thereby causing the CTIS controller to select the preprogrammed pressure corresponding to that mode. The controller attains the programmed pressure by issuing command signals to electronically controlled pneumatic components of the system which cooperate to automatically inflate or deflate the tires as required.
However, allowing an operator to program pressures from the control panel of the CTIS creates the possibility that the operator will program a tire pressure that is too low for the particular loads and/or speeds eventually encountered. If the programmed pressure is too low for a given load, speed or road condition, this may cause the air in the tires to rise in temperature to an excessive level which can lead to a reduced tire life.
Therefore there exists a need to account for tire pressure programming miscalculations and/or errors in order to optimize operating conditions while still providing the vehicle operator with needed control.